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Magnetic Composite for Efficient Adsorption of Iron and Manganese Ions from Aqueous Solution

Purwaningrum Widia, Hasanudin, Rachmat Addy, Riyanti Fahma, Hariani Poedji Loekitowati

Ecological Engineering & Environmental Technology

2023

Vol. 24, iss. 8

143--154

Iron Fe(III) and Manganese Mn(II) ions were effectively removed from aqueous solutions using a magnetic composite of Fe3O4/CaO/PDA, with CaO sourced from green mussel. The composite material was comprehensively characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy with Energy Dispersive – X-ray Spectroscopy (SEM-EDS), Brunauer, Emmett and Teller (BET) surface area analysis, Vibrating Sample Magnetometer (VSM). The impact of physicochemical adsorption parameters, such as solution pH, contact time, and concentration, were investigated. The Fe3O4/CaO/PDA composite displayed a value of 51.47 emu/g in saturation magnetization, enabling rapid separation through the use of an external magnet without the need for filtration. Optimal conditions for adsorbing Fe(III) ions were achieved at pH 3 and initial concentration of 400 mg/L with maximum efficiency reach after 60 minutes. Similarly, optimal conditions for Mn(II) ion adsorption were observed at pH 4 with the same contact time and initial concentration. The adsorption efficiencies were found to be 88.56% for Fe(III) and 75.65% for Mn(II). The pseudo-second-order model aptly depicted the kinetics associated with the adsorption of both types of ions while the Langmuir isotherm model indicated that monolayer adsorption takes place on the composite’s surface. The maximum capacities for adsorption is 322.58 mg/g for Fe(III) ions and 208.33 mg/g for Mn(II) ions. A negative Gibbs free energy value affirmed that the process occurs spontaneously under natural conditions. These results underscored the potential use of this Fe3O4/CaO/PDA composite in treating wastewater to remove heavy metal ions.

Modification of Calcium Oxide from Green Mussel Shell with Iron Oxide as a Potential Adsorbent for the Removal of Iron and Manganese Ions from Acid Mine Drainage

Purwaningrum Widia, Hasanudin Hasanudin, Rachmat Addy, Riyanti Fahma, Hariani Poedji Loekitowati

Journal of Ecological Engineering

2022

Vol. 23, nr 11

188--201

Acid mine drainage (AMD) has the characteristics of high heavy metal ion content and low pH. This study aimed to synthesize the CaO/Fe3O4 composite for the adsorption of iron and manganese ions from acid mine drainage. CaO was synthesized from the shells of green mussels (Perna viridis). The CaO/ Fe3O4 composites were characterized using XRD, BET surface area, SEM-EDS, and VSM. The functional groups of the composite before and after adsorption were analyzed using FTIR. The adsorption of Fe(II), Fe(III), and Mn(II) ions was carried out with the batch method to determine the effect of pH, contact time, and initial concentration of metal ions. The CaO/ Fe3O4 composite has magnetic properties, as indicated by the saturation magnetization value of 65.49 emu/g. The Langmuir and Freundlich isotherm models were used to describe the adsorption isotherm of the composite for Fe(II), Fe(III), and Mn(II) ions. Investigations were also conducted on adsorption kinetics, including pseudo-first-order and pseudo-second-order, as well as adsorption thermodynamics comprising free energy, enthalpy, and entropy. Pseudo-first-order and Langmuir isotherms are suitable to describe the adsorption of Fe(II), Fe(III), and Mn(II) ions with adsorption capacities of Fe(III) > Fe(II) > Mn(II). Moreover, the adsorption of all ions using the composite occurred spontaneously. The removal effectiveness for Fe and Mn ions from AMD using CaO/ Fe3O4 composite, reached 90.41 and 97.59%, respectively, in volume 100 mL AMD, composite mass 0.4 g, and a contact time of 60 minutes.